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CHAPTER 14
PROBLEM 14.1
A 30-g bullet is fired with a horizontal velocity of 450 m/s and
becomes embedded in block B which has a mass of 3 kg. After
the impact, block B slides on 30-kg carrier C until it impacts
the end of the carrier. Knowing the impact between B and C is
perfectly plastic and the coefficient of kinetic friction between
B and C is 0.2, determine (a) the velocity of the bullet and B
after the first impact, (b) the final velocity of the carrier.
PROBLEM 14.2
Two identical 1350-kg automobiles A and B are at
rest with their brakes released when B is struck by a
5400-kg truck C which is moving to the left at 8
km/h. A second collision then occurs when B strikes
A. Assuming the first collision is perfectly plastic
and the second collision is perfectly elastic,
determine the velocities of the three vehicles just
after the second collision.
PROBLEM 14.3
An airline employee tosses two suitcases, of weight 30 lb and
40 lb, respectively, onto a 50-lb baggage carrier in rapid
succession. Knowing that the carrier is initially at rest and that
the employee imparts a 9-ft/s horizontal velocity to the 30-lb
suitcase and a 6-ft/s horizontal velocity to the 40-lb suitcase,
determine the final velocity of the baggage carrier if the first
suitcase tossed onto the carrier is (a) the 30-lb suitcase,
(b) the 40-lb suitcase.
PROBLEM 14.3 (Continued)
Suitcase A impacts on suitcase B and carrier. Conservation of momentum:
ABCABC
WWWWWW
PROBLEM 14.4
A bullet is fired with a horizontal velocity of 1500 ft/s through
a 6-lb block A and becomes embedded in a 4.95-lb block B.
Knowing that blocks A and B start moving with velocities of
5 ft/s and 9 ft/s, respectively, determine (a) the weight of the
bullet, (b) its velocity as it travels from block A to block B.
PROBLEM 14.5
Two swimmers A and B, of weight 190 lb and 125 lb,
respectively, are at diagonally opposite corners of a floating raft
when they realize that the raft has broken away from its anchor.
Swimmer A immediately starts walking toward B at a speed of 2
ft/s relative to the raft. Knowing that the raft weighs 300 lb,
determine (a) the speed of the raft if B does not move, (b) the
speed with which B must walk toward A if the raft is not to
move.
PROBLEM 14.6
A 180-lb man and a 120-lb woman stand side by side at the
same end of a 300-lb boat, ready to dive, each with a 16-ft/s
velocity relative to the boat. Determine the velocity of the
boat after they have both dived, if (a) the woman dives first,
(b) the man dives first.
PROBLEM 14.7
A 40-Mg boxcar A is moving in a railroad switchyard with a velocity of 9 km/h toward cars B and C, which
are both at rest with their brakes off at a short distance from each other. Car B is a 25-Mg flatcar supporting a
30-Mg container, and car C is a 35-Mg boxcar. As the cars hit each other they get automatically and tightly
coupled. Determine the velocity of car A immediately after each of the two couplings, assuming that the
container (a) does not slide on the flatcar, (b) slides after the first coupling but hits a stop before the second
coupling occurs, (c) slides and hits the stop only after the second coupling has occurred.
